I recently experienced this exact issue so I thought i'd post to help anyone else who might run into it. The instructions say to change the method from MD5 to TRUST. In the windows logs I found that it could not load the pg_hba.conf file after making this change. If I changed the word 'TRUST' from upper case to 'trust' lower case then the file loaded and I was able to restart the services and proceed to change the password. Hope that helps.